Tape over the emitter limits emission angles and will allow more accurate location of the sensor. Once you have located the sensor you could probably remove the tape or replace it with paint. I use any command that works. This could be power On/Off, a menu navigation arrow, or whatever gets a quick, consistent response from the unit.

Usually, I can locate the sensor with my 'x-ray' technique. Sometimes I can shine through a plastic panel at an angle and see a shadow of the sensor. I use any command that works.